A method and apparatus of the general type to which the invention relates are the subject matter of German Patent Application No. P 35 20 069.3. In this earlier method and apparatus the branch stream of grit delivered to the roll mill is of such a quantity that an almost constant material level is maintained in the delivery shaft of the roll mill even when the quantity of fresh material changes.
The object of the invention is to provide an improved method and apparatus which enables in such a system the highest possible saving of energy and the lowest possible specific power requirement for crushing the material.